Edmonton keeping eye out for ‘relentless killer’ in tree canopy

In this Oct. 26, 2011 file photo, forester Jeff Wiegert, of the New York State Department of Environmental Conservation, removes emerald ash borer larvae from an ash tree at Esopus Bend Nature Preserve in Saugerties, N.Y. There are reports of a potential emerald ash borer beetle infestation in the Concord, N.H.-area. If the reports are confirmed, state officials will need to set up a quarantine to ensure infested ash trees, branches, logs, and firewood are contained. (AP Photo/Mike Groll, File)

The City of Edmonton is keeping an eye out for what it calls a “deceptively attractive” and “tremendously damaging” invasive pest that has been spreading in Canada.

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The emerald ash borer is a bright metallic green beetle the city said has proven to be a “relentless killer” of ash trees in North America – with 99 per cent of trees in an infested area dying within 6 years of the beetle’s arrival.

The insect, which is native to eastern Asia, lays its eggs in ash trees. The larvae then chew through the cambium layer of the bark and create tunnels that stop the flow of nutrients in damaged areas and eventually kill the tree.

Mike Jenkins, senior scientist with the City of Edmonton, said the beetles were first found in North America in the 1990s.

“It wasn’t until the mid 2000s that the damage really started getting noticed and it quickly spread from there,” Jenkins said. “(It) has spread into Ontario, into Quebec, several of the Maritime provinces. In 2018, they found it in Manitoba, and last year, they found it in Vancouver.”

The beetle has no native enemies in North America. While the city said woodpeckers do eat the larvae, they aren’t fast or efficient enough to stop the spread once populations of beetles are established.

Infested trees show dying branches, yellowing of their canopy, dying leaves that do not fall and peeling bark. Individual trees can be killed in as little as one to three years and can fall easily, damaging cars or property.

Jenkins said the insect hasn’t been found in Edmonton yet, but the city is keeping a close eye out because ash makes up about 20 per cent of its boulevard trees.

“If we wait until it’s too late, we’ll end up like Detroit, where they basically have no ash trees anymore and they spent millions of dollars just chopping down dead ash trees,” he added. “We just got Dutch elm disease last year. We don’t want emerald ash borer on top of that.”

Similar to the beetles that cause Dutch elm disease, the transport of firewood or wood products from infected regions is one of the easiest ways the pest is spread. The city said campers and travellers should burn firewood where it’s bought to prevent bringing in pests.

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The beetle is hard to detect in the early stages of infestation, but that’s when there is the best chance to control it. Jenkins said the city has set up special traps to monitor for beetles, and crews are doing surveys of the ash tree inventory.

The city is also asking residents to report any damaged trees or suspected beetles to 311.

“Early detection is the key. If we can get after it, we have a possibility of eradicating that pest or at least mitigating the damage that it’s doing,” he said.

For more information on emerald ash borers, visit the City of Edmonton’s website.